1. Field of the Invention
The invention relates generally to telecommunications network management, and more specifically to a system and method for analyzing, correlating, and presenting signaling network events.
2. Background Information
Modem telecommunications systems use out-of-band signaling to communicate information relating to connections and transactions. Out-of-band signaling is accomplished by a signaling network which is separate from the voice network. Several such signaling systems are commonly in use, such as, for example, ANSI SS7, ITU CCS7 and CCS6. Even though they may share some hardware, logically and operationally the signaling network is a separate network from the voice network.
The use of a separate signaling network allows numerous enhancements in telecommunications service. However, it also requires that the signaling network be managed separately from the voice network. In order to manage a signaling network, such as an SS7 network, three types of information must be collected and managed. The first is network topology information. This is information about the subnetworks which make up the overall network and about the connections within and between each subnetwork. The second type of information is traffic information. This is information about the message traffic in each subnetwork and in the overall network. The third type of information is alarm information. This is information about any problems with the signaling network which have been detected by network monitoring devices.
A typical SS7 network is illustrated in FIG. 1. A call-bearing telecommunications network makes use of matrix switches 102a/102b for switching customer traffic. These switches 102a/102b are conventional, such as, for example a DMS-250 manufactured by Northern Telecom, an AXE manufactured by Ericsson or a DEX-600 manufactured by Digital Switch Corporation. These switches 102a/102b are interconnected with voice-grade and data-grade call-bearing trunks. This interconnectivity, which is not illustrated in FIG. 1, may take on a large variety of configurations. Customers may include any person or entity which is served by the telecommunications network, for example, end users, foreign networks, serving areas, local exchange carriers, etc.
To utilize SS7 signaling, each switch is configured with special hardware and software that serves as an SS7 interface to that switch. This SS7 component is known generally as a Signal Point (SP) 102a/102b. The SP 102a/102b serves as an interface between the SS7 signaling network and the switch for call setup, processing, routing, and breakdown. The SP 102a/102b also serves as an SS7 signal converter for SS7 switches that must interface with non-SS7 switches.
Signal Transfer Points (STPs) 104a. . . 104f (collectively referred to as 104) are packet-switching communications devices used to switch and route SS7 signals. They are deployed in mated pairs, known as clusters, for redundancy and restoration. For example, in FIG. 1, STP 104a is mated with STP 104b in Regional Cluster 122, STP 104c is mated with STP 104d in Regional Cluster 124, and STP 104e is mated with STP 104f in Regional Cluster 126. A typical SS7 network contains a plurality of STP clusters 104; three such clusters are shown in FIG. 1 for illustrative purposes. Each STP cluster 104 serves a particular geographic region of SPs 102. A plurality of SPs 102 have primary SS7 links to each of two STPs 104 in a cluster. This serves as a primary homing arrangement. Only two SPs 102 are shown homing to Regional Cluster 126 in FIG. 1 for illustrative purposes; in reality, several SPs 102 will home on a particular STP cluster 104. SPs 102 will also generally have a secondary SS7 link to one or both STPs 104 in another cluster. This serves as a secondary homing arrangement.
The SS7 links that connect the various elements are identified as follows:
A links 110 connect an SP to each of its primary STPs (primary homing). PA1 B links 112 connect an STP in one cluster to an STP in another cluster. PA1 C links 114 connect one STP to the other STP in the same cluster. PA1 D links connect STPs between different carrier networks (not illustrated). PA1 E links 118 connect an SP to an STP that is not in its cluster (secondary homing). PA1 F links 120 connect two SPs to each other.
To interface two different carriers' networks, such as a Local Exchange Carrier (LEC) network with an Interexchange Carrier (IEC) network, STP clusters 104 from each carriers' network may be connected by D links or A links. SS7 provides standardized protocol for such an interface so that the signaling for a call that is being passed between an LEC and an IEC may also be transmitted.
When a switch receives and routes a customer call, the signaling for that call is received (or generated) by the attached SP 102. While intermachine trunks that connect the switches carry the customer's call, the signaling for that call is sent to an STP 104. The STP 104 routes the signal to either the SP 102 for the call-terminating switch, or to another STP 104 that will then route the signal to the SP 102 for the call-terminating switch.
SPs and STPs are machines that can generate information relating to network conditions and problems. However, the links are simply circuits: end-to-end connections which cannot themselves generate information. In order to extract circuit related information, Protocol Monitoring Units (PMUs) 106, as shown in FIG. 2, are used. PMUs 106 are deployed at switch sites and provide a monitoring tool independent of SPs and STPs. These devices, such as those manufactured by INET Inc. of Richardson, Tex., monitor the A, E, and F links of the SS7 network, as shown in FIG. 2. They generate fault and performance information for SS7 links.
As with any telecommunications network, an SS7 network is vulnerable to fiber cuts, other transmission outages, and device failures. Since an SS7 network carries all signaling required to deliver customer traffic, it is vital that any problems are detected and corrected quickly. Therefore, there is an essential need for a system that can monitor SS7 networks, analyze fault and performance information, and manage corrective actions. In order to perform these functions, the system must obtain and utilize information about the network topology, message traffic, network performance and network faults. This information must be correlated; that is, information must be matched with related information so as to provide a coherent view of the network.
Prior art SS7 network management systems, while performing these basic functions, have several shortcomings. Many require manual entry of network topology information, which is vulnerable to human error and delay topology updates. Configuration of these systems usually requires that the system be down for a period of time. While some prior art systems do obtain topology information in an automated process, these systems typically can obtain only a portion of the topology information which is required. These systems obtain the information only from PMUs, thereby neglecting network elements not connected to a PMU. Furthermore, these systems are typically intended to operate with only one particular vendor's PMU and cannot obtain information from other vendor's equipment. These prior art systems do not provide correlation between PMU events and events generated from other types of SS7 network elements. They also provide inflexible and proprietary analysis rules for event correlation.
A need exists for an SS7 network management system which can collect network topology, traffic, performance and fault information, correlate that information and display it in a coherent and useful manner to system operators. The system needs the capability of obtaining topology information in an automated, near-real-time manner from all network elements, regardless of type or vendor. A need exists for the system to allow system operators to select the display of information, in order to improve understandability of the information.